The present invention relates to a unit set for a robot, consisting of multiple types of units which are freely connected one with another to configure a robot, and particularly relates to a unit set for a robot including robot joint units for realizing the functions of joints by ensuring rotational driving of a rotating joint means facing outwards by means of a rotation driving means such as a built-in motor or the like, thereby rotationally driving other external components detachably connected to the rotating joint means.
Various types of such robot joint units have already been realized, with one typical example being disclosed in Japanese Examined Patent Application Publication No. 63-50155. According to this typical example, as shown in FIG. 20, a joint unit 1 is configured with an output rotating shaft 1c of a motor 1b equipped with a reducing device and assembled in an inner casing 1a, being connected to the inner face of an outer casing 1e via a coupling mechanism 1d, and with an outer casing center portion arm attaching portion 1f being fixed on the outer surface of the outer casing 1e surrounding the output rotating shaft 1c so as to rotate around the output rotating shaft 1c, wherein the perimeter portion of the outer casing 1e encloses the portion of the inner casing 1a shown at the lower side in the diagram so as to be relatively rotationally drivable, and wherein an outer casing perimeter portion arm attaching unit 1g is fixed on the surface of the outer casing 1e which encloses that portion of the inner casing 1a at the lower side of the diagram, an inner casing perimeter portion arm attaching unit 1h is fixed on the surface of the perimeter portion of the inner casing 1a at the upper side of the drawing, and a feedback unit arm attaching portion 1i which is uniaxially driven with the output rotating shaft 1c is fixed on an end face of the motor 1b appearing at the right side in the drawing, the end face being on the opposite side of the output rotating shaft 1c face of the motor 1b. With a conventional joint unit 1 having such a configuration, the outer casing center portion arm attaching portion If and feedback unit arm attaching portion 1i are rotationally driven by the motor 1b in the relative relation around a center axis of the output rotating shaft 1c indicated as an X axis in the figure, and the outer casing perimeter portion arm attaching portion 1g is rotationally driven by the motor 1b around the axis of the output rotating shaft 1c as one body together with the outer casing 1e, so as to ensure the advancing and retreating movements with regard to the inner casing perimeter portion arm attaching portion 1h fixed on the inner casing 1a, which portion 1h confronts a rotational track of the circumference of the outer casing 1e rotating around the axis X, thereby realizing a joint unit connectable in two orthogonal axial directions with uniaxial driving.
A typical example of a joint configuration of this type of joint units is disclosed in Japanese Unexamined Patent Application Publication No. 62-282886. According to this typical example, as shown in FIG. 21, a joint unit 2 which has the same configuration as in the above-described Japanese Examined Patent Application Publication No. 63-50155 comprises a pair of roll flanges 2a and 2b each corresponding to the outer casing center portion arm attaching portion 1f and feedback unit arm attaching portion 1i, and a pair of pitch flanges 2c and 2d each corresponding to the outer casing perimeter portion arm attaching portion 1g and inner casing perimeter portion arm attaching portion 1h, configured such that the pair of pitch flanges 2c and 2d are relatively rotationally driven around the common center axis of the roll flanges 2a and 2b. As for connecting implementations of joint units having such a configuration, a case wherein, as shown in FIG. 22(A), the relative rotational motion between the pair of roll flanges 2a and 2b is transmitted to an external component, a case wherein, as shown in FIG. 22(B), the rotational motion of the roll flanges 2a and 2b around the common center axis between the pitch flanges 2c and 2d is transmitted to an external component, and a case wherein, as shown in FIG. 22(C), the relative rotational motion of the pitch flange 2d with regard to the roll flange 2b around the common center axis of the roll flanges 2a and 2b is transmitted to an external component, can be conceived, so that various multi-joint functions can be realized by connecting a plurality of joint units 2 in the form of an arbitrary connecting implementation so as to assemble a multi-joint structure such as shown in FIG. 23. With the conventional joint units of this type, much work is being done in structural improvements directed to the reduction in size. Japanese Unexamined Patent Application Publication No. 10-249755 discloses a typical example of an improved structure. According to this typical example as shown in FIG. 24, a joint unit 3 is configured with a motor 3a and multi-stage reducing gear trains 3b being stored in a cubic casing 3c at high densities, wherein both ends 3e and 3f of an output rotating shaft 3d aligned with the last stage reducing gear respectively pass through both opposing faces of the casing 3c to appear outwards, and wherein a potentiometer 3h connected to an intermediate stage 3g of the gear trains 3b is stored in the casing 3c. 
Joint units through which two long arms are connected for being flexible are also used widely, and Japanese Examined Utility Model Registration Application Publication No. 1-8308 discloses working on an improved configuration of such types of joint units aimed at widening an angle of flexion. As shown in FIG. 25, a jointunit 6, which lies between a long first arm 4 and a long second arm 5 so as to connect the arms 4 and 5 in a flexing manner, stores therein: a driving gear 6a axially fitted to a driving motor; an intermediate gear 6c which is rotatably axially supported by a first axial pin 6b erected on the first arm 4 so as to mesh with the driving gear 6a; a first arm rotating gear 6d which rotates upon the axial pin 6b as one body together with the intermediate gear 6c in the same direction; and a second arm rotating gear 6h which is rotatably axially supported by a second axial pin 6e erected on the second arm 5, with a second arm rotating teeth 6g being formed on the perimeter of the second arm rotating gear 6h over a range of 180° so as to mesh with the first arm rotating teeth 6f formed on the perimeter of the first arm rotating gear 6d over a range of 180° thereupon. According to this improved configuration, upon the driving gear 6a being rotationally driven by means of the motor in the counter-clockwise direction in the drawing by the motor, the second arm rotating gear 6h rotates in the counter-clockwise direction in the drawing for encompassing the first arm rotating gear 6d, so as to ensure the orbital motion-like rotational motion whereby the joint unit 6 per se rotates in the counter-clockwise direction in the drawing while the second arm 5 also rotates in the counter-clockwise direction in the drawing due to the rotational motion on its center axis of the second arm rotating gear 6h in the counter-clockwise direction in the drawing. This results in the relative rotational angle of the second arm 5 in regard to the first arm 4 being twice that of the joint unit 6, so provided that 180° is selected for a rotational angle of the joint unit 6 per se, the meshing of the first arm rotating teeth 6f and the second arm rotating teeth 6g allows the relative rotational angle between the first and second arms 4 and 5 to reach 360°, thereby realizing the enlarged angle of flexion in the joint unit 6.
With regard to joint units for robots and robot structures constructed by assembling such joint units on the basis of such background arts, there has been the problem of insufficiencies in the point of the reduction in size by high-density installation of the components in the unit itself, in the point of the increased quality from the aspect of ensuring convenience in the assembling work and ensuring natural rotational motions, and in the point of the diversity of expressible configurations for a robot.